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92 lines
3.4 KiB
Text
92 lines
3.4 KiB
Text
[[mapping]]
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= Mapping
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[partintro]
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--
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Mapping is the process of defining how a document, and the fields it contains,
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are stored and indexed.
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Each document is a collection of fields, which each have their own
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<<mapping-types,data type>>. When mapping your data, you create a mapping
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definition, which contains a list of fields that are pertinent to the document.
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A mapping definition also includes <<mapping-fields,metadata fields>>, like the
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`_source` field, which customize how a document's associated metadata is
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handled.
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Use _dynamic mapping_ and _explicit mapping_ to define your data. Each method
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provides different benefits based on where you are in your data journey. For
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example, explicitly map fields where you don't want to use the defaults, or to
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gain greater control over which fields are created. You can then allow {es} to
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add other fields dynamically.
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NOTE: Before 7.0.0, the mapping definition included a type name.
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{es} 7.0.0 and later no longer accept a _default_ mapping. See <<removal-of-types>>.
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.Experiment with mapping options
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****
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<<runtime-search-request,Define runtime fields in a search request>> to
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experiment with different mapping options, and also fix mistakes in your index
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mapping values by overriding values in the mapping during the search request.
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****
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[discrete]
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[[mapping-dynamic]]
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== Dynamic mapping
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<<dynamic-field-mapping,Dynamic mapping>> allows you to experiment with
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and explore data when you’re just getting started. {es} adds new fields
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automatically, just by indexing a document. You can add fields to the top-level
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mapping, and to inner <<object,`object`>> and <<nested,`nested`>> fields.
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Use <<dynamic-templates,dynamic templates>> to define custom mappings that are
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applied to dynamically added fields based on the matching condition.
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[discrete]
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[[mapping-explicit]]
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== Explicit mapping
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<<explicit-mapping,Explicit mapping>> allows you to precisely choose how to
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define the mapping definition, such as:
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* Which string fields should be treated as full text fields.
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* Which fields contain numbers, dates, or geolocations.
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* The <<mapping-date-format,format>> of date values.
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* Custom rules to control the mapping for
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<<dynamic-mapping,dynamically added fields>>.
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Use <<runtime-mapping-fields,runtime fields>> to make schema changes without
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reindexing. You can use runtime fields in conjunction with indexed fields to
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balance resource usage and performance. Your index will be smaller, but with
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slower search performance.
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[discrete]
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[[mapping-limit-settings]]
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== Settings to prevent mapping explosion
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Defining too many fields in an index can lead to a mapping explosion, which can
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cause out of memory errors and difficult situations to recover from.
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Consider a situation where every new document inserted
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introduces new fields, such as with <<dynamic-mapping,dynamic mapping>>.
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Each new field is added to the index mapping, which can become a
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problem as the mapping grows.
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Use the <<mapping-settings-limit,mapping limit settings>> to limit the number
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of field mappings (created manually or dynamically) and prevent documents from
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causing a mapping explosion.
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--
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include::mapping/dynamic-mapping.asciidoc[]
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include::mapping/explicit-mapping.asciidoc[]
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include::mapping/runtime.asciidoc[]
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include::mapping/types.asciidoc[]
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include::mapping/fields.asciidoc[]
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include::mapping/params.asciidoc[]
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include::mapping/mapping-settings-limit.asciidoc[]
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include::mapping/removal_of_types.asciidoc[]
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